As someone developing Silverlight games, I'm very intereseted in Silveright gaining an install base.
Until now, it's been pretty difficult to get a good feel for just how large (or small) this Silverlight install-base is.
Recently, I came accross the following site: RIAStats.com
This site allows website owners to install a small chunk of java script that will record what RIA Plug-in visting users have installed. The site then gathers this data and presents it in two very easy to understand formats.
As I write this, RIAStats.com is tracking about 25000+ websites and is showing Silverlight 2.0 to be around 15%. Not bad considering it's still in beta.
Have a look!
http://www.riastats.com/